So how much power will this setup make?

By Clinton HulleyVW Polo Classic Project Car
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The Polo build is complete, at least I think it was. The car really ran well, allot better than I expected. There were some tweaks I still wanted to do but it was good enough for now. I took the Polo to the dyno shop I usually make use off. They strapped the polo done onto the Hyper Power Dyno. Outside the car, it sounds a lot more aggressive than when the car is driven.

Finally, the car was on the dyno and they did a run. The boost map was set at 1 bar boost as I first wanted to get used to the car. The Polo made 223kW and 360Nm torque. That was a lot more than the last time the car was on the dyno. I went home with a smile on my face. The nice thing about this setup was that it was still driveable. The car could be used as a daily driver and still have good fuel consumption. I was really impressed with what I have achieved with this setup.


Running into an issue.

I was driving the car for a few weeks now after it has been on the dyno. The car was a pleasure to drive. I was on my way to work one morning and got some heavy traffic that morning. The traffic was bumper to bumper. The traffic started moving and suddenly stopped. I tried to brake with the car and the brake pedal when straight to the floor. This was really scary. I pulled up the hand brake and stopped the car like that. The brakes were useless, for some reason the brakes faded away.

Once the traffic cleared up I could get the car up to 60 km/h. The brakes started working again. I found out that having the downpipe and compressor housing for the turbo so close to the brake master cylinder is not a good thing. The brake fluid started boiling in the traffic and that is why I lost my brakes. Going home that evening I had nice and free-flow traffic, that brakes weren’t an issue.

I order heat rap for the downpipe and heat cover for the compressor housing, That would take the heat radiation away from the brake master cylinder. This helped allot and the overall temps in the engine bay went down.

Polo 2 Liter 20 Valve engine after heat wrap was installed.

One morning on my way to work I accelerated with the Polo and suddenly the Boost shot up to 2 bar boost. The car pulled insanely hard. I tried it again and the same thing happened. The 3rd time I tried it the car started “pinging”. The engine was now on full working temp and the boost was just too high for normal 95 octane fuel.

So what was the issue?

I got home that evening and stripped off the wastegate. Of course, I had to let the car stand for a while as the wastegate, turbo and downpipe was so hot I could not get access to the wastegate without burning myself. I opened up the waste gate as the issue must be with it. What did I find? The diaphragm inside the wastegate had a tear in it. I found out that this was a common issue with the cheap Chinese waste gates.

The torn diaphragm on cheap Chinese wastegate.

Guess what there were no spares to replace the diaphragm and if you do get it replaced it is not to say that it will last.


So what is the solution?

I phoned around to try and find a better quality external wastegate. Most people were selling cheap Chinese waste gates. I just didn’t want to go through this again. I found a supplier that could get me an Xcell wastegate. This is the same wastegate that the drifting guys use. They were having really good results from this wastegate.

Xcell external wastegate

There is something that made this wastegate different from all the other units out there. This unit had a piston with a seal on it. It was nice and free moving. This meant that there wasn’t a diaphragm that could tear. I installed this unit. It was a straight swap with the Chinese unit. I took the car for a test run after that and the boost was once again under control.

So what was next?

As I have felt how the car pulls with 2 bar boost, I was very tempted to fit a high boost low boost switch in the car. If the switch is off the car must boost 1 bar max. When the switch is on then the car must boost whatever the boost map tells it to boost.


I bought a dashboard switch that I wired onto the signal line to the wastegate control valve. The spring inside the wastegate had to be changed so that the car could achieve the 1 bat boost on spring tension only. Doing this I could change the map to 1.5 bar or 2 bar boost max. If I want to drive with the higher boost I could then just add in octane booster to the fuel. Now I had 2 boost settings to play with.

This was round about the time I decided I want to get myself a Golf 5 GTI, this was a standard really strong car. The Polo will then become my weekend toy…


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